1. Field of the Invention
The present invention relates to a hybrid compressor device suitable for a refrigerant cycle system mounted in an idling stop vehicle, where a vehicle engine is stopped when the vehicle is temporally stopped.
2. Description of Related Art
Recently, the market for an idling stop vehicle has been increased to save fuel consumption. In a case where a compressor is driven only by an engine of the vehicle, when the vehicle is temporarily stopped, its engine is stopped, so that the compressor, driven by the engine, is also stopped in a refrigerant cycle system. In order to overcome this problem, in a conventional hybrid compressor device disclosed in JP-A-2000-130323 (corresponding to U.S. Pat. No. 6,375,436), driving force of the engine is transmitted to a pulley through a solenoid clutch, and one end of a rotational shaft of the compressor is connected to the pulley. Further, the other end of the rotational shaft of the compressor is connected to a motor. Accordingly, when the engine is stopped, the solenoid clutch is turned off, and the compressor is driven by the motor, so that the refrigerant cycle system can be operated regardless of the operation of the engine.
However, the hybrid compressor device requires the solenoid clutch for switching a driving source of the compressor between the engine in the operation of the engine, and the motor in the stop of the engine. Therefore, production cost of the hybrid compressor device is increased. Further, the compressor is operated by one of both the driving sources of the engine and the motor. Therefore, a discharge capacity of the compressor and a size thereof are need to be set based on a maximum heat load of the refrigerant cycle system in a driving force range of each driving source. For example, when a cool down mode (quickly cooling mode) is selected directly after the start of the vehicle in the summer, the heat load of the compressor becomes in maximum. Thus, the discharge capacity of the compressor and the size thereof are set so as to satisfy the maximum heat load, thereby increasing the size of the compressor.